P2647

A Rocker Arm Actuator Sys Stuck On Bank1

Indicator

It indicates that a short or open electrical circuit has been detected in the rocker arm actuator system for the intake (A) camshaft in engine bank 1. Note: The "A" identifies the intake camshaft, which is located to the intake side of the cylinder head. "Bank 1" denotes the engine bank that contains the number one cylinder.

Code Set Parameters

Abnormal voltage readings that vary more than 10-percent from reference value should cause a trouble code to be stored and a malfunction lamp may be illuminated.

Symptoms

A service engine soon lamp will be illuminated because a code is stored in the PCM. Roughness at idle, poor engine performance, and choppy acceleration may also accompany the service engine soon lamp.

Common Causes

Technicians report that common causes of this code are a faulty oil control valve, an open electrical circuit/connector related to the oil control valve, or a faulty PCM. A low oil level/pressure condition could contribute to this problem.

Common Misdiagnosis

Often components are replaced when low engine oil level, pressure, or viscosity proves to be the culprit. PCM failure is rare and should be considered only after all other possibilities have been exhausted.

Diagnosis

Crankshaft and camshaft positions are monitored using electromagnetic sensors

These sensors utilize relief holes in camshaft and crankshaft drive gears to provide signal interruption of the electromagnetic field

Interruptions in the electromagnetic field are seen by the PCM as square waveform patterns, which represent varying degrees of voltage

These variations in voltage are created using electromagnetic resistance in the 5-volt circuit

Some manufacturers use multiple crankshaft sensors to feed separate data streams to the PCM

Engines that are equipped with multiple camshafts generally use a camshaft sensor for each camshaft

Other automakers use notches cut into shafts or nodules that are permanently attached to interrupt the electromagnetic field

Often these notches or nodules are located near the rear or middle of the shaft, depending upon sensor placement

One manufacturer even places the crankshaft sensor on top of the transmission bell-housing and reads crankshaft position from interrupter holes in the flex plate

A proper diagnosis should begin with making sure that all engine timing indicators are properly aligned

After making sure that timing marks are aligned, test belt or chain deflection using manufacturer's specifications

VVT or VCT solenoids and circuitry should be tested if timing components prove to be properly aligned and in good working order

PCM and sensor failure are rare

Electrical wiring and connectors are more prone to fail than sensors, especially where oil or other corrosive fluids are present.
Several tools will be instrumental in successfully diagnosing this code

A suitable OBD-II scanner (or code reader), a digital volt/ohmmeter, and an oscilloscope will be most helpful in performing a successful diagnosis

A manufacturer's service manual (or the equivalent) will also be necessary

Always retest the system after repairs are completed to ensure success.
If all system wiring, connectors, and components (Including fuses) appear to be in normal working order, connect the scanner (or code reader) to the diagnostic connector and record all stored codes and freeze frame data

This information can be extremely helpful in diagnosing intermittent conditions that may have contributed to this code being stored

Continue by clearing the code and operating the vehicle to see if it returns

This will help to determine whether or not the malfunction is intermittent

After the codes are cleared, test drive the vehicle to see if the code returns

If the code fails to immediately return, you may have an intermittent condition

Intermittent conditions can prove to be quite a challenge to diagnose and in extreme cases may have to be allowed to worsen before a correct diagnosis can be made.
After disconnecting the connector from the affected sensor, check for a reference voltage signal (usually 5-volts.) and a ground at the connector end (key on/engine off)

If reference voltage and/or ground are not detected, disconnect the connector from the PCM and test all circuits for resistance and continuity

Consult the manufacturer's service manual for wiring diagrams, technical service bulletins, and/or flow charts that may be helpful

Repair or replace circuits, connectors, or components that do not comply with manufacturer's specifications, as required

After repairs are made, clear codes and test drive the vehicle to ensure that your repair has been successful.
If reference voltage and ground signals are present, reconnect the sensor and use the oscilloscope to monitor live data wave form patterns

Look for abnormalities in the wave form and replace the sensor in question if present

After repairs are made, clear codes and test drive the vehicle to ensure that your repair has been successful.
If wave for patterns appear to be normal, suspect a defective PCM

Remember, PCM failure is rare and replacement will require reprogramming

Some applications require camshaft and crankshaft sensor replacement in sets